Walter Bachmeier joined the Marine Corps in June, 1942. He trained in San Diego and immediately after boot camp was posted to Company L, 9th Marines. He served as a mortar gunner during training at Camp Pendleton, California, Cape Paerata, New Zealand, and in staging on the newly conquered island of Guadalcanal.

Bachmeier saw combat in the campaign for Bougainville and the Northern Solomons; he made his first landing on November 1, 1943, and fought through the winter before a tropical disease put him out of action. He was evacuated to Mobile Hospital #8 on Guadalcanal, and then sailed back across the Pacific for treatment in Seattle.

After recovering, Corporal Bachmeier was sent to Camp Pendleton to work in the base ordinance section. In late summer of 1945, he was deemed fit for active duty once again, and traveled to Hawaii to join Company A, 24th Marines as a mortar squad leader. The war ended only weeks later, and Bachmeier went on to serve with the ordinance company of the 6th Service Depot until his discharge in 1946.